Signal Transmitter and Methods for Transmitting Signals from Animals

ABSTRACT

Injectable transmitters are provided that can include a body with the body housing a power source and an oscillator, the injectable transmitter also including an antenna extending from the body, the body and antenna being of sufficient size to be injected through a 9 gauge needle. Radio frequency transmitters are provided that can include a body extending from a nose to a tail with the body housing a power source and RF signal generator components. The power source of the transmitter can define at least a portion of the nose of the body. The transmitters can have an antenna extending from the tail. Methods for attaching a radio frequency (RF) transmitter to an animal are provided. The methods can include providing an RF transmitter and providing an injection device having a needle of gauge of 9 or smaller; providing the RF transmitter into the injection device; and providing the RF transmitter through the 9 gauge or smaller needle and into the animal.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Patent ApplicationSer. No. 62/267,797 which was filed on Dec. 15, 2015, the entirety ofwhich is incorporated by reference herein.

STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY-SPONSOREDRESEARCH AND DEVELOPMENT

This invention was made with Government support under ContractDE-AC0576RL01830 awarded by the U.S. Department of Energy. TheGovernment has certain rights in the invention.

TECHNICAL FIELD

The present disclosure relates to signal transmitters and methods fortransmitting signals from animals. In particular embodiments, thetransmitters can be injectable and/or provide radio frequency signals.

BACKGROUND

Transmitters have revolutionized biologists' understanding of bothterrestrial and aquatic animal movements since they were first attachedto animals about 50 years ago. Accurate information on fish movement,for example, is needed to understand the impacts of hydroelectric damson fish migration and survival so that mitigation techniques can beapplied to recover endangered populations (or to prevent endangerment inthe first place). However, biologists are limited by the relativelylarge size of transmitters because of the potential to negatively impactand bias animal behavior. For example, the American Ornithologists'Union suggested that the transmitter weight should not exceed 5% of thebody weight of birds. American Society of Mammologists recommendtransmitter weight should be less than 5% of the bats' body weight.Miniature radio-frequency (RF) transmitters used for tracking smallaquatic, airborne, or terrestrial animals/objects that may be injectedare provided herein.

SUMMARY OF THE DISCLOSURE

Injectable transmitters are provided that can include a body with thebody housing a power source and an oscillator, the injectabletransmitter also including an antenna extending from the body, the bodyand antenna being of sufficient size to be injected through a 9 gaugeneedle.

Radio frequency transmitters are provided that can include a bodyextending from a nose to a tail with the body housing a power source andRF signal generator components. The power source of the transmitter candefine at least a portion of the nose of the body. The transmitters canhave an antenna extending from the tail.

Methods for attaching a radio frequency (RF) transmitter to an animalare provided. The methods can include providing an RF transmitter andproviding an injection device having a needle of gauge of 9 or smaller;providing the RF transmitter into the injection device; and providingthe RF transmitter through the 9 gauge or smaller needle and into theanimal.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a depiction of implantation of a transmitter according to anembodiment of the disclosure.

FIG. 2 is one perspective view of a transmitter according to anembodiment of the disclosure.

FIG. 3 is another perspective view of the transmitter of FIG. 2according to embodiment of the disclosure.

FIG. 4 is one perspective view of a transmitter according to anotherembodiment of the disclosure.

FIG. 5 is a depiction of a transmitter of the prior art and atransmitter of the present disclosure.

FIG. 6 is a block diagram depicting components of a transmitteraccording to an embodiment of the disclosure.

FIG. 7 is a block diagram depicting component of a transmitter accordingto another embodiment of the disclosure.

FIG. 8 is one perspective view of a transmitter according to anembodiment of the disclosure.

FIG. 9 is a depiction of a component of a transmitter according to anembodiment of the disclosure.

FIG. 10 is a depiction of another component of a transmitter accordingto an embodiment of the disclosure.

FIG. 11 is a part list of components of a transmitter according to anembodiment of the disclosure.

FIGS. 12A and 12B are circuit diagrams of component configurations of atransmitter without a crystal and with a crystal according to twoembodiments of the disclosure.

FIGS. 13-19 are graphical representations of animal wound data acquiredwhen implanting transmitters of the present disclosure according tomethods of the present disclosure.

DESCRIPTION

This disclosure is submitted in furtherance of the constitutionalpurposes of the U.S. Patent Laws “to promote the progress of science anduseful arts” (Article 1, Section 8).

To enhance the ability to study the survival of small fishes throughhydroelectric dams, a smaller and more powerful radio-frequency (RF)transmitter, which can be injected into fish using a 9-gauge needle, isprovided. Designs of two transmitters were developed: one that transmitscoded signals and one that transmits un-coded signals. To accommodatedifferent transmitter life requirements, each design can be configuredto provide a high or low signal strength.

The coded transmitter is 2.95 mm diameter and 11.85 mm long, and weighsmerely 160 mg. Depending on the ping rate (or PRI, pulse rate interval),the coded low-signal-strength transmitter has a projected service lifeof 11 days@2 s, 27 days@5 s and 52 days@10 s. By way of comparison, thesmallest commercially available radio frequency transmitter for animals(NTQ-1, Lotek Wireless Inc., Newmarket, ON, Canada) has 6-58% loweroperating lifetimes, despite being somewhat larger than the discloseddesigns. The coded high-signal-strength transmitter has a comparableservice life to the Lotek NTQ-1.

The un-coded transmitter is 2.95 mm diameter and 11.22 mm long, andweighs 152 mg. It provides even longer service life than the codedtransmitter. Its low-signal-strength variant can last 15 days@2 s, 37days@5 s and 69 days@10 s.

Definitive determination of a preferred surgical implantation method wascomplicated due to several factors in the bio-effects evaluation.However, at the end of the study (day 14), the Incision-Cath method hadthe lowest percentage of open wounds (4.2%), the smallest wound size(1.14 mm²), and the lowest percentage of transmitter loss (10%), and islikely the best method for transmitter implantation based on this pilotevaluation. Although the injection method had the fastest implantationtime, and may allow cost-savings for telemetry studies with large samplesizes of tagged fish, the percentage of dropped transmitters (47.5%) wasthe highest of any treatment.

Referring to FIG. 1, a method for attaching a radio frequencytransmitter 16 through a needle 14 into an animal 12 is depicted.Transmitter 16 is as described herein and needle 14 has a gauge of 9 orless. As depicted, transmitter 16 can be injected into animal 12. Thiscan be a subcutaneous injection if desired or more or less invasiveinjection. Animal 12 can be any ambulatory being including but notlimited to fish for example.

The transmitter can have a cylindrical body with a diameter of 2.95 mmor less to be compatible with a 9-gauge needle, for example. Thetransmitter can be encapsulated in an epoxy resin for rigidity and thetransmitter body can be coated with a 25-μm layer of Parylene-C toprovide waterproofness and/or bio-compatibility.

Referring next to FIG. 2, transmitter 16 a is shown according to anembodiment of the disclosure. According to this embodiment, transmitter16 a includes a body 20 and an antenna 21. Body 20 can extend between anose 22 and a tail 24. Preferably, injection of the transmitter proceedsnose first, for example. Transmitter 16 a can include a power source 26that can define at least a portion of the nose. This power source can bea battery such as that battery disclosed in U.S. patent application Ser.No. 14/014,035 filed Aug. 29, 2013, the entirety of which isincorporated by reference herein. Transmitter 16 a can include RF signalgenerating components such as voltage regulator 28, capacitor 29 andoscillator 30.

Referring next to FIG. 3, according to another view of transmitter 16 a,additional components are shown in operable alignment. For example,transmitter 16 a can include LED 31 (blue), microcontroller 35,capacitor 32, resistor 33, and another capacitor 34.

Other component configurations of the transmitters are contemplated. Forexample, transmitter 16 b is shown in FIG. 4. Transmitter 16 b caninclude LED 31 mounted next to oscillator 30, for example.

Referring next to FIG. 5, a transmitter of the present disclosure ispictured (bottom) side by side with the commercially available radiofrequency transmitter referenced above (Lotek NTQ-1, top).

The transmitters can include three components: an antenna component fortransmitting RF signals, a circuit board component containing thecontrolling circuitry, and a cylindrical micro-battery component thatpowers the transmitter. The antenna can be a Teflon PFA(perfluoroalkoxy)-coated stainless steel wire that has a diameter of38.1 μm. The length of the antenna can be varied to achieve the desiredresonance frequency of the transmitter (e.g., 17.8 cm=˜164 MHz). To meetthe transmitter life goal, the transmitter can use a Li/CF_(x)micro-battery consisting of lithium metal anode and carbon fluoridecathode, which has a capacity of 6 mAh and is 6 mm long. Compared to thetraditional silver oxide button-cell batteries, which are commonly usedin small commercial radio transmitters, the Li/CF_(x) batteries have theadvantages of high energy and power density as well as high averageoperating voltage (3.1-3.4 volts), long shelf life and a wide operatingtemperature range.

To fabricate the prototype transmitter, the micro-battery can be firstattached to the circuit board using a silver-filled epoxy such as the8331 (MG Chemicals, Ontario, Canada). The antenna can be soldered to thecircuit board. For encapsulation, this RF transmitter assembly can becoated with an insulating epoxy such as the EPO-TEK 301 epoxy (EpoxyTechnology Inc., Billerica, Mass.) using a flexible mold, which can bemade from flexible materials (e.g. silicone rubber). The mold can havecavities that define the shape of the transmitter. After the RFtransmitter assembly is placed into the cavity, the insulating epoxy canbe injected into the bottom of the cavity using a syringe with a smallneedle until the epoxy fills up the cavity. The mold may be left tostand overnight for the epoxy to cure. After removal from the mold, thetransmitter may be gently sanded with sand paper and polished using arotary polishing tool to eliminate any sharp edges or burrs. Finally,the RF transmitter can be coated with 25-μm thick Parylene-C to becomewaterproof and/or bio-compatible.

Two different designs (Option 1 and Option 2 hereinafter) of theinjectable RF transmitter are provided as example implementations, butother implementations are contemplated. Option 1 transmits un-coded RFsignals at a set ping rate, whereas Option 2 transmits coded RF signals.

A first embodiment (i.e. Option 1) can be 11.22 millimeters in lengthand weighs less than 152 milligrams.

A second embodiment (i.e. Option 2) can have an extra crystal to controlthe timing of RF signal so that it can generate coded RF signals. Thesecond embodiment can be about 0.63 mm longer and 8 mg heavier than thefirst embodiment.

A block diagram of the first embodiment (i.e. Option 1) transmitter isshown in FIG. 6. This design includes a microcontroller, aresistor-capacitor (RC) network, a light emitting diode (LED), alow-dropout voltage (LDO) regulator and a programmable oscillator.

The microcontroller controls various circuits and functions within theinjectable RF transmitter. It executes embedded firmware (source code)that defines its operation, which includes turning the programmableoscillator on and off to control the transmitted signal.

The RC circuit isolates the microcontroller from the voltage drop of thebattery and keeps it from entering brownout state.

The LED provides an optical link for programming through a personalcomputer. This component is not used in the typical manner: rather thangenerating light when a voltage is applied across its terminals, the LEDgenerates a voltage across its terminals when exposed to ultravioletlight. A configuration apparatus (not shown) may utilize a USB-to-TTLconverter circuit and a second LED to convert serial commands from apersonal computer to a coded series of “on” and “off” pulses of light,which then may be converted back into electrical signals by the firstLED on the transmitter. This first LED is then coupled to one of thepins on the microcontroller. The above mechanism provides a small yeteffective way to activate the microcontroller and specify operatingparameters such as the PRI.

The LDO regulator outputs a fixed voltage at 1.8 V to power theprogrammable oscillator, because the typical input voltage of theprogrammable oscillator ranges from 1.6 V to 2.2 V.

The programmable oscillator generates a symmetric square wave signal.The Fourier series of a square wave is

${{square}(t)} = {{\frac{4}{\pi}{\sum\limits_{n = 1}^{\infty}\frac{\sin \left( {n\; t} \right)}{n}}} = {\frac{4}{\pi}\left( {\frac{\sin (t)}{1} + \frac{\sin \left( {3t} \right)}{3} + \frac{\sin \left( {5t} \right)}{5} + \ldots}\mspace{14mu} \right)}}$

A square wave only contains odd harmonics and the amplitude decreases ininverse portion to harmonic order n. For this application, the FCCfrequency range can be 164˜168 MHz. The programmable oscillator can beprogramed to 54.667˜56.000 MHz for high-strength signals to generate asine wave at 164˜168 MHz using the 3rd harmonic. This option consumes acurrent of 2.7 mA. The programmable oscillator can alternatively beprogramed to 32.8˜33.6 MHz for low-strength signals using the 5thharmonic. This option consumes a current of 2.1 mA. The duration of theun-coded RF signal can be set to about 16 ms using the internal clock ofthe microcontroller.

A block diagram of the second embodiment (i.e. Option 2) transmitter isshown in FIG. 7. This design includes a microcontroller that uses anexternal clock signal from an added quartz crystal to accurately controlthe timing of the oscillator. This mechanism allows the transmitter togenerate coded RF signals. The microcontroller can also use the crystalto calibrate its internal clock. To allow multiple transmittersbroadcasting on the same frequency, a pattern of pulses unique to eachindividual transmitter can be used.

Referring next to FIG. 8, a depiction of the second embodiment (i.e.Option 2) transmitter 16 c that includes crystal 80 and additionalcapacitors 81 and 82 is shown. Referring to FIG. 9, a more detailed viewof the oscillator 30, voltage regulator 28 and capacitor 29 are shownassociated with a circuit board of the transmitter. Referring to FIG.10, additional components of the same circuit board, but opposing sidecan include microcontroller 35, capacitor 32, resistor 33, LED 31, andcapacitor 29.

Referring next to FIG. 11 a general electronic component parts list isprovided that can be arranged in accordance with the circuit diagram ofFIGS. 12A and 12B. FIG. 12A is representative of the first embodiment(i.e. Option 1) transmitter and FIG. 12B is representative of the secondembodiment (i.e. Option 2) transmitter.

Signal output can be compared between the two prototype transmitters andthe smallest commercially available transmitter. The test can beperformed outdoors to minimize the effects of electromagnetic noise andother signals. The test transmitters can be placed about 10-cm apart andparallel to each other and the signal receiver (Sigma Eight Orionreceiver with an omnidirectional whip antenna) was located about 6 maway. The receiver antenna was arranged perpendicular to the transmitterantennas. All transmitters and receiver/antenna remained in the sameplace during the test.

Hatchery-reared spring Chinook salmon (Oncorhynchus tshawytscha) wereused for all bio-effects experiments. After hatching, the juveniles wereheld in cold water until July 2015, when they were slowly acclimated toa water temperature of 12° C. to allow them to grow to an appropriatesize for juvenile salmonid radio transmitter implantation (i.e., >95mm). For 2 months prior to tagging and for the duration of this study,fish remained at 12° C. (±2° C.). Food was restricted for 24 hours priorto and 24 hours following implantation. On the day of implantation, fishranged from 103-153 mm (mean=129.9 mm) in fork length (FL) and weighed10.9-36.8 g (mean=23.6 g). All tools were disinfected (by ultravioletlight for surgical blade) or sterilized (by autoclave for stainlesssteel needles and catheters) prior to use. The 9-gauge needles were newon the day of tagging. After first use with the injection treatment,they were autoclaved and still very sharp for the 9 ga-needle withcatheter treatment.

Since implantation time was an important variable in this study, ratherthan randomize the treatment order throughout the tagging day, eachtreatment was completed in a block. Using this design, the tagger wasable to standardize the technique of implantation and to becomeefficient with the process. Thus, theoretically, this tagging orderproduced the fastest implantation times for each of the three treatmentswith the radio transmitter tested. In addition, the efficiency isrepresentative of the process in which fish would be tagged in a fieldstudy where only one technique is used.

“Dummy” transmitters of the second embodiment described above that wereequal in dimensions and mass to the functioning transmitter (i.e., thelarger prototype suitable for coded transmitters) were used for thebioeffects study. It had dimensions of 2.95 mm×2.95 mm×11.85 mm andcontained within its volume an 8.4 mm long passive integratedtransponder (PIT) tag (HPT8, Biomark). This PIT tag permitted uniqueidentification of the dummy transmitter if it were shed during thepost-tagging holding period. Currently in a radio telemetry study in theWillamette River basin, PIT tags also are being implanted alongsideradio transmitters in smolts for PIT tag detection downstream of FosterDam. Therefore, for this laboratory study, a 12.5 mm PIT tag (HPT12,Biomark) was implanted along with the dummy radio transmitter.Unfortunately, the presence of 2 PIT tags in a single fish makes neithertag detectable due to their proximity. However, every tag dropped couldbe immediately identifiable. At the completion of this study, fish wereagain identifiable during necropsy by scanning each tag individually.

On Sep. 15, 2015, fish were netted from a 4-ft diameter circular rearingtank and placed in a 20-L bucket filled with aerated river water. One ata time, fish were placed in an anesthetic bucket with a dosage of 80mg/L Tricaine Methanesulfonate for ˜3 min or after a complete loss ofequilibrium. Fish were then immediately weighed, measured, and tag codesassigned. The tagger then implanted the anesthetized fish using one ofthree treatment methods: surgical incision with catheter (akaIncision-Cath), 9-gauge needle injection (aka Injection), and 9-gaugeneedle with catheter (aka 9 GA-Cath). For both of the cathetertreatments, fish were placed on a wet, grooved, surgery pad (coated withPolyAqua, a water conditioner) for stabilization and their gills wereirrigated with fresh water through rubber tubing from a gravity-fedtank. For the injection treatment, fish were stabilized in the tagger'shand. Detailed descriptions of the treatments are explained below.

Method 1: Surgical incision with catheter (Incision-Cath)—With the fishfacing ventral side up, a surgical blade was used to make ˜3-mm incisionon the linea alba (mid-ventral line). The incision was made ˜5 mmanterior of the pelvic girdle. To place the antenna through the bodywall, a 19-gauge stainless steel needle shielded with a 16-gaugestainless steel catheter was carefully guided through the body cavityposterior to the pelvic girdle. Then, the 19-ga needle was unshielded tomake a hole through the body wall. The needle remained in the fish whilethe catheter was pulled back out through the incision. The end of thetransmitter antenna was then threaded through the tubing of the needle.Both the needle and antenna were pulled posteriorly until the needle wasout of the fish and the antenna was threaded through the body wall.Next, the PIT tag was inserted into the peritoneal cavity. Lastly, thetransmitter body was guided into the peritoneal cavity as the antennawas gently guided posteriorly. Unlike most field radio tagging studies,a suture was not used to close the incision. Recent laboratory studiesusing an injectable acoustic transmitter of similar size showed 100%long-term transmitter retention with a ˜3 mm incision in salmon as smallas 80 mm in length (unpublished data).

Method 2: 9-gauge needle injection (Injection)—To prepare the tags forinjection, first the transmitter was loaded into the 9-ga needle byinserting the rounded transmitter end through the hub end of the needle.If the dummy transmitter body was slightly too wide to be insertedthrough the hub, then the slower loading method was used. The slowermethod consisted of threading a short section of the transmitter antennathrough the 16-ga catheter and guiding it through the pointed end of theneedle. The antenna could not be threaded directly through the needleand hub (without the aid of the catheter) because the end of the antennawould catch on an edge inside the needle and the antenna could becomekinked. After loading the transmitter into the needle, the needle hubwas screwed onto an implanter (Biomark MK10 implanter). Modifications tothe implanter included removal of the spring and notching the tip of theimplanter to permit the antenna wire to hang outside the implanter body.Next, the PIT tag was loaded into the pointed end of the needle and thiscompleted the preparation phase of tagging. The fish was then heldventral side up with its head facing away from the tagger. Using abevel-down technique similar to that described by Cook et al. (2014),the needle was used to puncture the body wall ˜3-5 mm anterior of thepelvic girdle and ˜5 mm off the linea alba, on the left side of thefish. The needle was inserted to a shallow depth to create a hole justlarge enough for the transmitter. With a plunge of the implanter, thePIT tag, followed by the dummy transmitter, were injected anteriorlyinto the peritoneal cavity. Pressure was applied to the wound with theleft thumb to ensure the transmitter was retained while the needle wasdrawn out of the fish and the antenna moved forward through theimplanter and needle.

Method 3: 9-gauge needle with catheter (9 GA-Cath)—Before the fish wasplaced on the surgery pad, the 19-ga needle, shielded with the 16-gacatheter, was inserted into the hub end of the 9-ga needle (theimplanter was not used for this technique). With the fish facing ventralside up on the pad, the 9-ga needle was used to make a small opening (˜3mm; equal to the width of the transmitter) near the distal end of theright pectoral fin ˜3-5 mm from the linea alba. Then, the shielded 19-ganeedle was carefully guided through the body cavity posterior to thepelvic girdle. The 19-ga needle was unshielded to make a hole throughthe body wall. The needle remained in the fish while the catheter and9-ga needle were pulled away from the fish. The end of the transmitterantenna was then threaded through the tubing of the needle. Both theneedle and antenna were pulled posteriorly until the needle was out ofthe fish and the antenna was threaded through the body wall. Next, thePIT tag was inserted into the peritoneal cavity. Lastly, the transmitterbody was guided into the peritoneal cavity as the antenna was gentlyguided posteriorly.

After tagging, images were taken of the implantation wounds: two woundseach for fish implanted by methods 1 or 3, and one wound each for fishimplanted by method 2. Fish were placed ventral-side up on a pad andthey were supplied with water through rubber tubing throughout theimaging process. They were returned quickly to a recovery bucketsupplied with aerated river water. Once ˜10 fish were recovered, theywere transferred to the holding tank where they resided for the durationof the study.

At 14 days post-surgery, fish were euthanized in 250 mg/L MS-222. Imageswere taken of the wounds as the external fish assessment was completed.Wounds were examined for openness, redness/inflammation, and ulceration.It was also noted whether the antenna was still present outside of thefish. The fish was then necropsied to determine radio transmitter andPIT tag retention and to identify the fish (by scanning each tag).Evaluation of tag encapsulation and/or adhesions was also completed atthis time. Measurements of the wound area were made post-hoc.

All analyses were done with JMP version 7 (The SAS Institute, Cary,N.C.) at an alpha=0.05. Assumptions of equal variances and normalitywere verified prior to parametric statistical procedures.

The signal strengths of both high and low-signal-strength variants ofthe second embodiment prototype were tested to compare with that of theLotek NTQ-2. Both of the prototype transmitters were found to beconsistently about 10 dB stronger (−76 and −77 dBm, respectively for thehigh and low-signal-strength designs) than the Lotek NTQ-2's (−88 dBm).

Transmitters of the present disclosure also have similar or betterservice life compared to Lotek NTQ-1 and NTQ-2. The energy consumptionof the transmitters was calculated by

E _(trans) V*I*T

V is the battery voltage in volts; we choose an average value of 2.5Volts in the service life calculations. I is the average currentconsumed during transmission and T is the duration of each transmission.

For transmitters of the first embodiment, the duration is 16 ms for eachRF signal transmission. For low signal strength, current I is 2.1 mA andthe energy consumption is 84 μJ. For high signal strength, current I is2.7 mA and the energy consumption is 105 μJ.

For transmitters of the second embodiment, the total pulse duration isabout 22 ms for each RF signal transmission. For low signal strength,current I is 2.1 mA, the energy consumption is 115.5 μJ. For high signalstrength, current I is 2.7 mA, the energy consumption is 148.5 μJ.

The service life calculation in Table 1 was based on the batterycapacity 6 mAh, constant static current 0.5 uA that flows through thetransmitter circuit, PRI.

The total energy of battery in transmitters can be calculated by

E _(battery) =V*C*3600/1000

V is the battery voltage in volts, C is the battery capacity in mAh, thenumber 3600 is used to convert hours to seconds and 1000 is used toconvert mAh to Ah.

The total energy of battery can also be calculated by

E _(battery) =E _(total) _(_) _(trans) +E _(s)

E_(total) _(_) _(trans) is the total energy consumed by transmissionsthroughout the service life of the transmitter and E_(s) is the energyconsumed by the static current that constantly flows through thetransmitter circuit.

Therefore, the total energy of battery can be expressed as:

$E_{battery} = {{{E_{trans}*n} + {V*I_{s}*T}} = {{{E_{trans}*\frac{T}{P\; R\; I}} + {V*I_{s}*T}} = {\left( {\frac{E_{trans}}{P\; R\; I} + {V*I_{s}}} \right)*T}}}$

E_(trans) is energy consumption of each transmission, n is total numberof transmission throughout the service life. I_(s) is constant staticcurrent 0.5 μA that flows through the transmitter circuit. PRI is thepulse rate interval (ping rate) and T is the service life in seconds.

Because the total number of transmission n can be calculated by

$n = \frac{T}{P\; R\; I}$

The service life in days can be calculated as

$T = {\frac{E_{battery}}{\frac{E_{trans}}{P\; R\; I} + {V*I_{s}}} = {{{\frac{V*C*{3600/1000}}{\frac{E_{trans}}{P\; R\; I} + {V*I_{s}}}/3600}/24} = \frac{V*{{C/1000}/24}}{\frac{E_{trans}}{P\; R\; I} + {V*I_{s}}}}}$

It is worth noting that the actual service life of the transmitter isusually slightly longer than the projected values based on thisequation, because the battery voltage gradually decreases at a slow rateas it discharges, which consequently causes the E_(trans) decreases overtime.

Table 1 provides the size, weight, and calculated service lifecomparisons between the Lotek transmitters and the example transmitters.

TABLE 1 The comparison of Lotek, example transmitters Size WeightCalculated Life (days) w × h × l (air) 2 s 5 s 10 s 60 s Transmitter(mm) (mg) PRI PRI PRI PRI Lotek NTQ-1 5*3*10 260 10 21 33 59 NTQ-25*3*10 310 16 33 52 94 1^(st) Embodiment Low signal strength 2.95*11.22152 15 37 69 245 High signal strength 2.95*11.22 152 12 30 56 217 2^(nd)Embodiment Low signal strength 2.95*11.85 160 11 27 52 206 High signalstrength 2.95*11.85 160 9 21 41 176

The actual service life of the first embodiment transmitter was testedat a 3 s PRI (Table 2). The test results are consistent with theprojected value obtained using the equation described above.

TABLE 2 The prototype RF transmitter life testing results 1^(st)Embodiment (3 s PRI) Calculated Life Measured Life Transmitter (days)(days) Low-signal-strength 23 30 Transmitter (test sample 1)Low-signal-strength 23 24 Transmitter (test sample 2)

No mortalities occurred throughout the 14-day duration of theexperiment; however, surgery time and surgery maladies differed betweenthe three surgical techniques/treatments. Implantation timesignificantly differed between the 3 treatment types (P<0.0001) with theInjection treatment having the fastest time (mean=12 s, SE=1.3 s) andthe 9 GA-Cath and Incision-Cath treatments having times of 48 s (SE=1.3)and 45 s (SE=1.3), respectively (FIG. 13). Preparation time for theInjection treatment was also measured for 15 surgeries, and whencombined with surgery time, resulted in an average total surgery time of29 seconds (SE=3.14).

FIG. 13 depicts Implantation time (seconds) of the 3 surgicalimplantation treatments. The horizontal line in the green diamondrepresents the mean, upper and lower bounds of the diamond represent25^(th) and 75^(th) percentiles, and blue horizontal lines indicates5^(th) and 95^(th) percentiles. Means comparisons are also shown in theright panel using the Tukey-Kramer HSD test.

The percentage of dropped tags and dropped antennas differedsignificantly between treatments (tags, P=0.0002; antennas, P=0.001).Injection treatment fish lost the most tags (47.5%) whereas 9 GA-Cath(15%) and Incision-Cath (10%) lost fewer tags (FIG. 14). Injection fishalso lost the most antennas (65%) compared to either 9 GA-Cath (27.5%)or Incision-Cath (40%). The difference in percentages between lostantennas and tags was due to the antennas falling off of the tag bodiesand the tag bodies remaining inside the fish.

FIG. 14 depicts percentages of fish that retained (dotted “Yes”) or lost(cross-hatched, “No”) their RF transmitters through the final day of thestudy (Day 14).

Wound area at Day 0 (day of tagging) for the Injection-Incision site(i.e., hole made that tag body was inserted through) was significantlydifferent between treatments (P<0.0001; FIG. 15). The Injectiontreatment wound (mean=2.04 mm², SE=0.07) and 9 GA-Cath wound (mean=1.84mm², SE=0.07) were relatively large and statistically similar whereasthe Incision-Cath wound was significantly smaller (mean=0.63 mm²; TukeyHSD). Catheter site wound area did not differ between the 9 GA-Cath andIncision-Cath treatments (P=0.0885; FIG. 16). Specifically comparing thewound area of the antenna-exit holes for each treatment (i.e., same asinjection site for Injection treatment), the Injection treatment wassignificantly larger than either the 9 GA-Cath or Incision-Cath woundmade by the catheter, which likely played a role in whether fishretained or lost their transmitters.

FIG. 15 depicts a comparison of the wound area of the injection-incisionsite at day 0. The horizontal line in the green diamond represents themean, upper and lower bounds of the diamond represent 25^(th) and75^(th) percentiles, and blue horizontal lines indicates 5^(th) and95^(th) percentiles.

FIG. 16 depicts a comparison of the wound area of the catheter (Cath)site at day 0. The horizontal line in the green diamond represents themean, upper and lower bounds of the diamond represent 25^(th) and75^(th) percentiles, and blue horizontal lines indicates 5^(th) and95^(th) percentiles.

Wound area on Day 14 (end of study) was significantly different amongtreatment groups (P<0.0001; FIG. 17) with Injection fish having thelargest wound area (5.77 mm²), 9 GA-Cath having an intermediate woundarea (3.17 mm²), and Incision-Cath having the smallest wound area (1.14mm²). However, it's important to note that fish that lost their tags orantennas were not included in these results because of inherent biasthat losing a tag/antenna would have had on wound healing; thus, thisanalysis (and Figure) only include fish that retained their transmitterand antenna. Similar to Day 0, the wound area of the catheter site didnot differ between 9 GA-Cath and Incision-Cath treatments (P=0.5592,FIG. 18).

FIG. 17 depicts a comparison of the wound area of the injection-incision(Inj-Inc) site at day 14 (end of study) for each of the 3 surgicaltreatments. The horizontal line in the green diamond represents themean, upper and lower bounds of the diamond represent 25^(th) and75^(th) percentiles, and blue horizontal lines indicates 5^(th) and95^(th) percentiles. Tukey-Kramer HSD comparisons are included forreference.

FIG. 18 depicts a comparison of the wound area of the catheter (Cath)site at day 14. The horizontal line in the green diamond represents themean, upper and lower bounds of the diamond represent 25^(th) and75^(th) percentiles, and blue horizontal lines indicates 5^(th) and95^(th) percentiles.

Predicting dropped transmitters. Using a stepwise multivariate modelingprocedure, tag loss was significantly related to the treatment method(P<0.0001) as well as fish fork length (P=0.0168). However, thepredictability of the final model was relatively weak (r²=0.1837) withtreatment contributing most to the model's prediction power (r²=0.1391).Original predictor variables included treatment, fish fork length,inj-inc wound area at day 0, and catheter wound area at day 0.

Of the variables measured on the day 14 necropsy, only wound opennesswas significantly different among treatments (P<0.0001; Figure). AllInjection treatment fish (N=13) had open injection wounds (i.e.,unhealed with visible opening to internal organs) on day 14 whereas24.1% (7 of 29) of the 9 GA-Cath treatment and 4.2% (1 of 24) of theIncision-Cath fish had open injection wounds.

No significant differences were found between catheter wound openness ofthe two catheter treatments (P=0.8916), redness/inflammation (P=0.3916),tag encapsulation (P=0.4931), or tag adhesion (P=0.2548; Table 3). Noulcerations were present on any necropsied fish.

FIG. 19 depicts percentage of fish, by surgical treatment, with openIncision-Injection (Inc-Inj) wounds (dotted, “Yes”) or closed wounds(cross-hatched, “No”) during day 14 necropsies.

TABLE 3 Percentages of necropsy maladies (variable) by surgicaltreatment groups and wound locations. Treatment/Wound Variable Injection9 GA-Cath/tag 9 GA-Cath/cath Inc-Cath/tag Inc-Cath/cath P Catheter woundopen NA NA  3.5% (1 of 29) NA 4.2% (1 of 24)  0.8916Redness/inflammation 15.4% (2 of 13) 3.5% (1 of 29) 10.3% (3 of 29) 4.2%(1 of 24) 8.3% (2 of 240 0.3916 present Tag encapsulation 30.8% (4 of13) 51.7% (15 of 29) NA 37.5% (9 of 24)  NA 0.4931 Tag adhesion  7.7% (1of 13)  0% (0 of 29) NA 4.2% (1 of 24) NA 0.2548

Definitive determination of a preferred surgical implantation method wascomplicated due to several factors in the bio-effects evaluation.However, at the end of the study (day 14), the Incision-Cath method hadthe lowest percentage of open wounds (4.2%), the smallest wound size(1.14 mm2), and the lowest percentage of tag loss (10%), and is likelythe best method for transmitter implantation based on this pilotevaluation. Although the injection method had the fastest implantationtime, and may allow cost-savings for telemetry studies with large samplesizes of tagged fish, the percentage of dropped tags (47.5%) was thehighest of any treatment.

Tag loss and antenna loss for all implantation treatments was likelyaffected and biased by the kinking and tangling of the antenna material.At least 10 transmitter antennas were found to be tangled with eachother, either within fish, or after tags had fallen out of fish.Further, the Injection, 9 GA-Cath, and Incision-Cath treatments lost17.5%, 12.5%, and 30% of their antennas, respectively, while tag bodiesremained inside study fish. However, because fish from all treatmentswere located within the same tank during the 14 day observation period,we assume that all treatments had equal probability of having theirantenna tangled and despite this, there were differences in tag losswith the Injection technique having greatest tag loss (47.5%) and the 9GA-Cath (15%) and Incision-Cath (10%) methods having lower loss. Thus,we presume that tag loss was related more to the size of the openwound—the Injection technique had the largest wounds on both day 0 (2.04mm2) and day 14 (5.77 mm2)—rather than due to the tangling of antennasalone.

Surgical implantation time is approximately the time that a fish is “outof water” during the surgical procedure; either on a surgical pad orheld in the tagger's hand. The out of water time for the Injectiontreatment was faster than the 2 catheter techniques and would likelyhave beneficial effects with respect to fish health and survival.However, researchers should be cautious when relating the time savingsof the Injection technique to budget/cost savings because the additionalpreparation time required to load the tags in the implanter needleranged from 5-50 s (i.e. total load+implant time=13-59 s; mean=29seconds, SE=3.14). Otherwise, if the tagger did not load the needlethemselves, budgets would likely require an extra person tasked withloading tags for the entire tagging day. Alternatively, smallmodifications could be made to the transmitter or 9-gaugeneedle/implanter to keep loading times to ˜5 s, thereby potentiallyimproving the cost-savings estimates.

The pilot laboratory evaluation using the prototype injectable radiotransmitter has provided an array of ideas on methods to improve andrefine the transmitter design and implantation techniques. Qualitativeimprovements to the transmitter design based on the laboratoryevaluation include creating a smoother antenna coating, using adifferent antenna material, and standardizing the tag body size. Asmoother antenna coating would have likely reduced the implantationtimes of the Incision-Cath and 9 GA-Cath techniques due to jagged“barbs” of the coating that snagged on the surgery materials as theantenna was threaded through the 19-gauge needle. Tagging times weremuch faster (i.e., ˜30 s) using uncoated transmitters on dead fishduring our pre-experiment “practice” tagging. A smoother antenna coatingor a different antenna material would also likely minimize the tanglingof antennas in holding tanks following implantation, which is animportant factor to consider for future field studies that necessitateholding fish in close proximity in small buckets. Standardizing the tagbody size would also likely reduce the implantation times of theInjection technique. With a more consistent body size, the transmittercould be consistently loaded from the hub end, which resulted in taggingload times of about 5 s.

Improvements to surgical tools could also be beneficial for improvingthe tagging technique and reducing surgery time for the Injection and 9GA-Cath techniques studied in this pilot evaluation. Modifications tothe tubing used for the 9-gauge needle in the Injection technique couldfurther reduce tag-loading time. Additionally, modification of thenotched implanter used in the Injection technique could reduceimplantation time by reducing antenna snags in the implanter duringtransmitter injection. The 9-gauge needle used in the 9 GA-Cathtreatment was also cumbersome and designing a combinationneedle-implanter may improve tag retention, reduce wound size, andreduce implantation time.

In compliance with the statute, embodiments of the invention have beendescribed in language more or less specific as to structural andmethodical features. It is to be understood, however, that the entireinvention is not limited to the specific features and/or embodimentsshown and/or described, since the disclosed embodiments comprise formsof putting the invention into effect.

1. An injectable transmitter comprising: a body, the body housing apower source and an oscillator; and an antenna extending from the body,the body and tail being of sufficient size to be injected through a 9gauge needle.
 2. The injectable transmitter of claim 1 furthercomprising: an LED; RC network; microcontroller; and low dropoutregulator.
 3. The injectable transmitter of claim 1 further comprising:an LED; RC network; microcontroller; low dropout regulator; and crystal.4. The injectable transmitter of claim 1 wherein the body furthercomprises a waterproof housing.
 5. The injectable transmitter of claim 1wherein the body is substantially capsule in shape.
 6. The injectabletransmitter of claim 1 wherein the body is less than 12 mm in length. 7.The injectable transmitter of claim 1 wherein the body has a diameter ofless than 3 mm in one cross section.
 8. A radio frequency transmittercomprising: a body extending from a nose to a tail, the body housing apower source and RF signal generator components, the power sourcedefining at least a portion of the nose of the body; and an antennaextending from the tail.
 9. The radio frequency transmitter of claim 8wherein the power source is a battery.
 10. The radio frequencytransmitter of claim 8 wherein the power source is a cylindricalmicro-battery
 11. The radio frequency transmitter of claim 10 whereinthe battery comprises a Li/CF_(x) micro-battery comprising a lithiummetal anode and a carbon fluoride cathode.
 12. The radio frequencytransmitter of claim 10 wherein the battery has a capacity of 6 mAh andis less than 6 mm long.
 13. The radio frequency transmitter of claim 8wherein the antenna comprises Teflon PFA (perfluoroalkoxy)-coatedstainless steel wire
 14. The radio frequency transmitter of claim 8wherein the antenna defines a diameter of less than 38.1 μm and a lengthof less than 17.8 cm.
 15. A method for attaching a radio frequency (RF)transmitter to an animal, the method comprising: providing an RFtransmitter and providing an injection device having a needle of gaugeof 9 or smaller; providing the RF transmitter into the injection device;and providing the RF transmitter through the 9 gauge or smaller needleand into the animal.
 16. The method of claim 15 wherein the animal is afish.
 17. The method of claim 16 wherein the animal is a salmon.
 18. Themethod of claim 15 wherein the RF transmitter includes an antenna. 19.The method of claim 15 further comprising tracking the animal using anRF signal generated by the RF transmitter.
 20. The method of claim 15further comprising providing a signal from the RF transmitter for atleast 24 days.